#include	"mail.h"/* Delete the current record specified by the mail structure. * This function is called by mail_delete() and mail_store(), * after the record has been located by _mail_find(). */int_mail_dodelete(MAIL *mail){	int		i;	char	*ptr;	off_t	freeptr, saveptr;		/* Set data buffer to all blanks */	for (ptr = mail->datbuf, i = 0; i < mail->datlen - 1; i++)		*ptr++ = ' ';	*ptr = 0;	/* null terminate for _mail_writedat() */		/* Set key to blanks */	ptr = mail->idxbuf;	while (*ptr)		*ptr++ = ' ';		/* We have to lock the free list */	if (writew_lock(mail->idxfd, FREE_OFF, SEEK_SET, 1) < 0)		err_dump("writew_lock error");		/* Write the data record with all blanks */	_mail_writedat(mail, mail->datbuf, mail->datoff, SEEK_SET);		/* Read the free list pointer.  Its value becomes the		   chain ptr field of the deleted index record.  This means		   the deleted record becomes the head of the free list. */	freeptr = _mail_readptr(mail, FREE_OFF);		/* Save the contents of index record chain ptr,		   before it's rewritten by _mail_writeidx(). */	saveptr = mail->ptrval;		/* Rewrite the index record.  This also rewrites the length		   of the index record, the data offset, and the data length,		   none of which has changed, but that's OK. */	_mail_writeidx(mail,NULL, mail->idxoff, SEEK_SET, freeptr);		/* Write the new free list pointer */	_mail_writeptr(mail, FREE_OFF, mail->idxoff);		/* Rewrite the chain ptr that pointed to this record		   being deleted.  Recall that _mail_find() sets mail->ptroff		   to point to this chain ptr.  We set this chain ptr		   to the contents of the deleted record's chain ptr,		   saveptr, which can be either zero or nonzero. */	_mail_writeptr(mail, mail->ptroff, saveptr);	if (un_lock(mail->idxfd, FREE_OFF, SEEK_SET, 1) < 0)		err_dump("un_lock error");	return(0);}